To Boldly Go Where No Astronomer Has Gone Before
By Sarah-Jane CollinsFebruary 26, 2012
Scientists are lining up to take the Pathfinder Telescope for a tour around the universe.
Silence stretches out across the wide expanse of Western Australia that lies within the radio zone that is home to the Murchison Radio-Astronomy Observatory, approximately 315 kilometres northeast of the mining town of Geraldton, 400-odd kilometres up the beach from Perth.
There is nothing around for many kilometres, and scientists say that's why it's perfect. Murchison is home to the Australian Square Kilometre Array Pathfinder (ASKAP) telescope, which is due to be completed next year. And with a bit of luck, it also may become the home of the Square Kilometre Array (SKA) - an international scientific endeavour to map the universe using a series of radio telescopes linked together to allow faster, more complete and in-depth readings of galaxies near and far than ever before.
Australia and New Zealand, working together, have put in a bid for the SKA, as it's known, and are competing with African nations led by South Africa, for the chance to host it. The decision is imminent, expected in the next two months; a technical committee already has handed down its recommendation in confidence.
But whether or not the SKA is built on our shores, its precursor - the Pathfinder, or ASKAP - is set to transform completely our knowledge of the universe. It may perhaps even determine the type of work the SKA takes on, once it has a home.
A CSIRO project, backed by around AUD150 million in government funding, Pathfinder is expected to start surveying the sky in late 2013. It will be so powerful that surveys that used to take 10 years will now be possible in one night.
Ilana Feain, the Pathfinder project scientist, says the new telescope is something that has never been seen before in radio astronomy. Not only will it work faster, it will cover greater tracts of the universe than anything that has come before.
"ASKAP is going to be a brand new, extremely powerful telescope that will be capable of doing science that can't be done with other instruments. It allows us to see the universe with an extremely large field of view. Traditionally, radio telescopes have been like single-pixel cameras - literally one pixel - [but] we've got very innovative technology… which can be thought of as multi-pixel cameras, allowing us to do extremely wide imaging," she says.
"ASKAP itself will be about 30 pixels, and what that means is we can survey the universe somewhere between 30 and 100 times faster than we currently do with existing technology."
Sort of like that moment in The Wizard of Oz when Dorothy opens the door and steps into Munchkinland. That might sound simplistic, but the elegance of the Pathfinder is its ability to explore the universe in ways scientists had only dreamed of before.
To give you some idea of the scale of the Pathfinder, some statistics: When complete, it will have 36 antennas, 12 metres in diameter each, and a total collecting area of 4,000 square metres. Its construction began in 2009 and it's a worldwide scientific collaboration, with scientists across the globe working on the project, from countries including the United Kingdom, Germany, Canada and the Netherlands.
"We're going to look at galaxy formation and evolution both in the near universe and also pushing right out to the most distant universe tens of billions of light years away… We'll be looking at how galaxies form across cosmic time," Feain says.
"One of the things this technology allows us to do is capture images of the sky in very high fidelity in very short timeframes, so what we'll be able to do, which we haven't been able to do before with radio telescopes, is to look for objects in the sky - bursting supernovas, gamma-ray bursts and so forth - that vary very quickly. And we'll be able to look for variables - very high-energy, very powerful events that vary on very short time scales."
Scientists attached to the project anticipate that it will allow observation of many elements of our universe that are currently impossible to track, detect, or view at all.
Importantly, the Pathfinder will give scientists the opportunity to observe the structure and interactions of young galaxies that are much closer to the Big Bang - meaning they are newer than our own - allowing them to observe the way that galaxies like the Milky Way have developed over time.
And, of course, there could be discoveries that no one has expected or anticipated.
"It's very hard to say in advance what we expect to discover, but we know we will be finding objects that were born only a couple of 100 million years after the Big Bang, that have black holes at their center, that are a billion times the mass of our sun and are producing out of these massive black holes jets of radiation that propagate across the universe and are influencing around them the way the galaxy is formed," Feain says.
"We know that we'll find very gaseous galaxies [and] as a galaxy grows and grows it kind of eats its own gas to form stars. And so by looking at the gas in galaxies as a function of time in the universe you learn a lot… we hope to solve some of the key mysteries around what we don't understand around how stars form and how galaxies form around black holes."
In the first five years of its operation, 75 per cent of the Pathfinder's time will be taken up by large-scale surveys that will provide the clearest picture yet of the universe. Feain says radio astronomers from around the world applied to use the Pathfinder for ground-breaking new studies, and the 10 best ones were picked by an independent panel of experts.
Tara Murphy, from Sydney University, is a lead scientist on one of those projects - VAST: an ASKAP Survey for Variables and Slow Transients. VAST is an attempt to study the constant movement and development of the universe.
"In optical astronomy you know that stars twinkle and planets move and all that, but in radio astronomy the technology that we'd had meant that typically when we look at the sky we see distant galaxies, extremely distant galaxies and things that stiffen over in our own galaxy and they look the same day after day," Murphy says.
"Now, with ASKAP, the key thing that we'll have is the ability to survey the sky - a large part of the sky - every single night, and so we'll see things changing on short human timescales that we haven't been able to see before.
"For example, we'll see supernova explosions, we'll see gamma-ray bursts, we'll see extreme scattering events, we'll see all of these different phenomena that we've only been able to see a tiny little bit... So it's very exciting for radio astronomy."
Murphy, who has a background in both radio astronomy and programming, says VAST will have practical applications, too, because the software being developed to monitor what the Pathfinder sees in the sky each night will be able to process large volumes of data and sift through it effectively.
"The way we've done things in the past has been surprisingly manual actually, but in this case every five seconds you're getting that data - even if you have all the PhD students you cannot look at it all, so you have to rely on the algorithms," she says.
That means software must be written to deal with it, which then can be used in other fields that require fast data consumption and sophisticated sorting.
"The astronomy, that just helps us understand the universe; it's more the technology that will cross over," Murphy says.
The astronomy though, will be groundbreaking.
"It's radical. If you can imagine that you suddenly get technology that is that much better - you can do lots of new science," she says.
Murphy, who says she jumped at the chance to submit a project for consideration when the Pathfinder project put out the call, is obviously enthused by the possibilities.
She is not the only one. Baerbel Koribalski is a lead scientist on the Widefield ASKAP L-Band Legacy All-Sky Blind (WALLABY) survey - another Pathfinder study that is mapping galaxies. She says Pathfinder will provide the kind of view of the skies that will make discovery much easier.
"If you think of the moon, the moon has a diameter of about half a degree, so you could stack a couple of moons up and down and make this giant field of view that we've never ever had before with any other telescope," Koribalski says. "So we built this telescope to be able to do hydrogen surveys for galaxies far away from our own galaxy - over the whole sky."
WALLABY will look at the entire southern sky, and whatever parts of the northern sky it can reach. Koribalski says her team expects to find upwards of half a million galaxies.
"We've done an all-sky survey before a few years back with the Parkes telescope, and we discovered about 5,000 galaxies and we have a good understanding of the distribution of those…. So we've taken that knowledge and extrapolated from there, using our physical processes, and predicted that we'd see about half a million galaxies in this particular survey. That might end up maybe 600,000 or 700,000 or 500,000 - that's impossible to predict," she says.
"Having a large survey, doing this for one year - it's just going to more or less supersede anything that currently exists in the literature in neutral hydrogen gas."
Pathfinder's 10 major projects, including WALLABY and VAST, involve more than 360 scientists from 131 institutions around the world. About a third are Australians or New Zealanders, with 30 per cent from North America, 28 per cent from Europe and the remaining 9 per cent from other nations.
One of the key features of the Pathfinder telescope that differentiates it from other radio telescopes, such as the Parkes observatory, is its three moving axes, with the entire dish rotating in unison with the sky. This is a completely new way of detecting radio waves, and it will allow a different view of the sky.
Feain says the Pathfinder already has begun test surveys.
"All of the 36 antennae will be in the observatory this year. Currently we are doing very small numbers of test observations and we expect to ramp up to full observations towards the end of next year… but the testing, and even some of the science, will begin coming out this year."
It is true that the scientific community is all abuzz with anticipation over who will host the SKA and what sort of discoveries it may make, but an operational SKA is still years away, and in the interim the Pathfinder will be probing deeper into the universe than ever before.
Does that mean the Pathfinder, or its yet-to-be-built big brother, the SKA, might find other life out there in the universe?
"One of the key science goals for the SKA is looking for proteins… but as much as the public loves it, it's not really the aim of these telescopes. There's a whole concept around the discovery of the unknown. You don't ever know what you're going to discover and you have to design your instruments with the flexibility to continue to discover," she says.
Australia, enormous and sparsely populated, is one of the only places in the world that could conceivably host such ambitious telescopes. Once the great frontier for European explorers, the red dirt and vast expanses of our unforgiving outback are again the site of some of the boldest and most mysterious exploration being undertaken today. What comes next is wholly unpredictable, with the potential to totally change our understanding of the universe.